Crane tip alarm

ABSTRACT

The invention provides several tilt indication/warning devices for use on equipment or vehicles having a rotating, angularly upstanding boom such as fire-fighting and rescue apparatus and particularly mobile cranes such as used to shift containerized cargo between the holds of ships and land carriers. A prospective topple condition caused by movement of the weight carrying boom is monitored with a multi-stage warning by a gimbal-mounted light-carrying pendulum gravitationally suspendable above the chassis with its vertically descending beam displaceable over a plurality of arcuate photoelectric receivers arranged in a circle. Intermediate its length, the pendulum also carries an electric-conducting ring which on swinging contacts an electrically-conducting arcuate segment in the direction of chassis-tilt thus giving a subsequent stage alarm which may be connected to inactivate the boom-lowering mechanism as well as effecting a final audio-visual alert in the cab.

United States Patent [1 1 Hoge [ Nov. 19, 1974 1 1 CRANE TIP ALARM [76]Inventor: Daniel W. Hoge, 1529 Lynton St.,

Wilmington, Calif. 90744 22 Filed: Feb. 9, 1973 211 App]. No.: 331,218

[52] US. Cl 212/69, 212/39 MS, 116/124 F, 340/190, 340/267 C [51] Int;Cl. B66C 23/84, G080 21/00 [58] Field of Search 212/39 MS, 69; 340/188R, 340/188 CH, 190, 267 C; 116/124 F; 222/55 [56] References CitedUNITED STATES PATENTS 2,273,330 2/1942 Robinson 222/55 2,772,411 11/1956Cooper 116/124 F 3,035,712 5/1962 Nowack 212/39 MS 3,183,496 5/1965Go1dstein.... 340/196;188 R X 3,217,895 11/1965 Noll et a1. 212/39 MSFOREIGN PATENTS OR APPLICATIONS 1,531,166 11/1969 Germany 212/39 MS1,155,191 6/1969 Great Britain 212/39 MS 233,200 12/1968 U.S.S.R. 212/39MS 1,160,150 5/1959 Germany 212/39 MS Primary E.\'aminerRobert B. ReevesAssistant Examiner-H. S. Lane Attorney, Agent, or Firm-Howard L. Johnson[5 7] ABSTRACT The invention provides several tilt indication/warningdevices for use on equipment or vehicles having a rotating, angularlyupstanding boom such as fire-fighting and rescue apparatus andparticularly mobile cranes such as used to shift containerized cargobetween the holds of ships and land carriers.

A prospective topple condition caused by movement of the weight carryingboom is monitored with a multi-stage warning by a gimbal-mountedlight-carrying pendulum gravitationally suspendable above the chassiswith its vertically descending beam displaceable over a plurality ofarcuate photoelectric receivers arranged in a circle. Intermediate itslength, the pendulum also carries an electric-conducting ring which onswinging contacts an electrically-conducting arcuate segment in thedirection of chassis-tilt thus giving a subsequent stage alarm which maybe connected to inactivate the boom-lowering mechanism as well aseffecting a final audio-visual alert in the cab,

9 Claims, 21 Drawing Figures PATENTE unv 1 sum 3 848,7 5 U sum 1 or 7 rPATEME :52: I 91974 SHEU 2 OF 7 FIG.5

PATENIE 140v 1 91974 SHEET 0F 7 RIGHT FRONT AUDIO LEFT FRONT FIG.9

PATENTE :mv I 91974 SIIEEI 50F 7 I IIIIIII FIG.

PATENIEL HEY I 9 3.848.750

saw 7 or 7 REAR lOO

FIG. 19

FRONT REAR FWD. CENTER FIG. 20

FIG. 2|

CRANE TIP ALARM BACKGROUND OF THE INVENTION This invention relates toprogressive tilt-monitoring or upset-warning devices for equipment suchas cargomoving cranes and the like, which cranes are characterized by aplurality of angularly articulated, extension arms which areground-supported to achieve positional stability which may be threatenedby a rotationally swinging and vertically-angled boom which terminallyis adapted to lift and move heavy cargo. Such heavy duty cranestypically are used to shift containerized cargobetween holds of shipsand land carriers. As technology has resulted in heavier and largercontainerized packages, the booms required to handle them have becomelonger, and the vehicular operating base to which the boom is attachedhas become more top-heavy. Overturn of the total assembly has occurredin some instances, producing loss of the operators life as well asdestruction of equipment and cargo, especially when the whole tumblesinto the ocean.

Safety regulations now require warning signal devices which correlatethe angular position of the boom with the weight of the suspended load;if the latter exceeds a preset limit, it may act to cancel the pick-up.However, once the cargo-piece is hung from the boom and the latterstarts to slant downward, rotate and/or extend longitudinally, thestability of the base of the crane may become extremely precarious andsuddenly fail, dependent upon how the moving cargo-piece isprogressively deployed relative to the ground anchorage of the vehicle.

With a mobile crane, after being wheeled to an operating site,Outriggers are extended from the chassis along both sides so as to formfour corners of a theoretical rectangle with the ground-supportedoutriggers vertically articulated to the chassis and withthe vehicularwheels usually remaining on the ground. Weightshift thereafter caused bythe swinging boom-carryingcargo may then tilt the chassis and liftwheels off the ground along one side or the other. While a minimumamount of such tilt is familiar to and tolerated by crane operators, itis when this condition approaches a topple-point that they need to beimmediately aware of .it so as to avert calamity. However, because therotating operators cab normally exhibits appreciable wobble, by his ownsenses the operator cannot accurately gage to what extent the chassis istilted beneath him, that is, how much an edge of the vehicle (or itswheels) may be raised off the ground.

In relation to this situation it has been proposed that in cranes havinghydraulic-operated Outriggers, when all wheels have been thereby raisedoff the ground (to obtain an operative position), the fluid pressure ofthe several outrigger rams be balanced against a preset standard ofvariance so as to actuate an on-off type alarm (U.S. Pat. No.3,680,714).

BRIEF STATEMENT OF THE INVENTION By the present invention, the state ofstability or threathened instability of the crane assembly iscontinuously monitored by evaluation of the tilting or changecontact'ofa chassis-mounted plunger, but more conveniently this is effected bysuch a plunger disposed in contact with each outrigger arm; such atactile plunger has a short induction mass carried by its proximatelength which passes axially and progressively through successiveelectrical coils secured to the chassis, whereby warning signals ofincreasing danger are sent to a panel in the operators cab'so as toactivate successive alarms with increasing amount of tilt. In place ofthe multiple coil, induction plunger, an electric eye monitoring devicemay be used at each outrigger. Altemately or in addition, there isprovided a chassis supported pendulum-type unit which by progressiveamounts of tilt, activates successive alarms in response to progressivetilt of the chassis; only a single such unit need be used for anassembly and it is initially suspended perpendicular to the horizon eventhough the chassis itself may be positioned at an angle. With any ofthese forms of multi-stage alarm, the last stage may also be connectedto cancel or override a selected crane-operating element whichaccentuates topplerisk, such as the boom-lowering mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of a mobilecrane with a tiltwaming device mounted at each outrigger.

FIGS. 2 and 3 are elevational segmental views of an outrigger laterallyextending from the chassis of the crane, with the chassis mountedwarning device shown making contact respectively with an outrigger arm,and with the ground support surface.

FIG. 4 is a similar view with the overlying bed of the crane contactedby a chassis-mounted plunger.

FIG. 5 is a vertical sectional view through the warning device withportions of the contact plunger and surrounding coils appearing inelevation.

FIG. 6 is an elevational view of an outrigger projecting from thechassis which carries an alternate electric eye form of tilt-warningdevice.

FIG. 7 is a top plan view of the construction of FIG. 6.

FIG. 8 is a transverse sectional view taken along line 8-8 of FIG. 6.

FIG. 9 is a semi-schematic elevational view of the indicator and controlpanel in the operators cab of the crane.

FIG. 10 is an electrical wiring diagram showing connection of fourtilt-waming devices to the panel elements of FIG. 9.

FIG. 11 is a vertical axial sectional view through the cylindricalhousing of another tilt-waming device.

which is particularly adapted to be mounted on the chassis of a crane orother tiltable assembly.

FIG. 12 is a top plan view of the same.

FIG. 13 is a horizontal sectional view taken along line 13-13 of FIG.11. p 7

FIG. 14 is an enlarged vertical sectional view of a portion of thependulum mount of FIG. 11. 7

FIG. 15 is an elevational view of the tilt-waming device of FIG. 11 heldin leveling mount for attachment to the chassis.

FIG. 16 is a top plan view of the leveling mount and I tilt-wamingdevice of FIG. 15.

FIG. 17 is a sectional view taken along line l7l7 of FIG. 16.

FIG. 18 is a horizontal sectional view taken along the I line 18l8 ofFIG. 15.

FIG. 19 is an enlarged horizontal sectional view similar to FIG. 13 butshowing a modified conductive disk formed of four insulated quadrants.

FIG. 20 is a top plan view of the composite photoreceiver used with theconstruction of FIG. 19.

FIG. 21 is a side elevational view of the photoreceiver of FIG. 20.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT A typical mobile craneillustrated in FIG. 1 has an elongated bed or body 12 juxtaposed above achassis 13 (FIG. 4) which at its forward end supports a vehicle motor 14and drivers compartment 16 situated above a pair of steering wheels 17,18. The rear body portion is carried upon four dual wheels 19, 20, 21,22 which are relatively clustered together so as to support the mainportion of the weight when the crane is in operation. A rotary platformbearing an operators cab 24 plus mutually parallel cable drum 26 andhorizontal boom axle 28 is disposed atop a power-operated turntable 30.A pair of cables 32, 33 extends forward lengthwise along the boom 34 toterminal cargo-attachment means (not shown). Extensible and retractablefrom the sides of the chassis (upon the vehicle being parked) are. fouroutriggers, each consisting of a transverse stabilizer arm 36, 38, 40,42, with a terminal, flared ground-support pad 37, 39, 41, 43. Thecontact pads are generally spaced outward in four directions from theapproximate center of the turntable in order to try to evenly distributethe load at the turntable. Obviously, the weakest position for boomstability would be midway between two corners of the rectangle formed bythe outrigger pads.

In operation, ,a load suspended from the end of the boom may be found tobe swinging back and forth more-or-less in a line parallel to the boom,and on its outward swing it is evident that such movement can jeopardisethe stability of the whole assembly. To suppress this swing, theoperator may try simultaneously to lower the boom and reel up the cargoin order to bring the two together. In such a critical situationhowever, too great a lowering of the weighted boom may move the centerof gravity sufficiently outward so as to, cause the whole to suddenlytopple. In addition, atthis critical time, watching the ship rise andfall in the water rhythmically may deaden the operators own sense ofbalance.-

The tilt sensing device detailed in FIG. 5 consists of a cylindricaltubular housing 47 having a contact piston 49 projecting partway fromone end thereof. Axially centered within the housing is a spool 50formed with a central longitudinal channel 52 which receives an innerlength of the piston thus disposed for limited reciprocal movementtherealong. Endwise in both directions from the spool, the axial channelis continued by short tube lengths 53, 54, the latter length joining anintermediate-diameter tubular housing 55 which holds a coil spring 56biased to resist compression. One end of the spring abuts an annularplate 57 carried by the plunger which is thus normally urged outwardfrom the housed position of FIG. 5.

The spool 50 carries a series of axially spaced insulating disks 58, 60,62, 64, the spool lengths therebetween being wound with electricallyconducting wire so as to form separate coils 59, 61, 63. The length ofthe piston rod 47 which is within the spool is formed of non conductingmaterial such as porcelain, wood, synthetic plastic, etc. and near itsinner end it carries a concentration of magnetisable material such asnickel-steel or other ferrous material. As progressive extension of therod 47 brings the induction charge 65 within each coil 59, 61, 63, acurrent is induced in the respective coil which registers on themonitoring panel in the cab.

As seen particularly in FIG. 2, the housing 47 may be secured to thechassis by a narrow mounting bracket 66 so that the distal end of theplunger 49 rests atop the outrigger arm 36. Altemately (or in addition)the chassis-connected housing 47 can dispose the contact plunger 49against the overlying body 12 (FIG. 4) or directly against the groundsupport S (FIG. 3). In the latter case, the device 45 must be set forground contact each time the mobile crane is moved to a new location.However, the other two mounting locations remain continuously functionalwithout intermittent adjustment. The chassis-to-body mounted plunger ofFIG. 4 does not produce as much movement of the plunger 49 as the groundconnection (FIG. 3) or connection to an articulated outrigger arm (FIG.2), but is useful in situations where the Outriggers cannot be extendedonto a stable area because of absence of firm ground support; forexample, when the crane must be parked on a narrow causeway or alongsidewet sand or mud in which the support pad 37 would sink.

In the construction shown in FIGS. 6-8, progressive tilting of theoutrigger arm 36a is indicated by interruption of successive beams of(visible or invisible) radiation linearly directed from a bank ofemitters 67a-b-c to corresponding receivers 68a-b-c so as to passthrough aligned slots 44 of a pair of scanning plates 69, 7 l which areattached to opposite sides of the stabilizer arm 36a. Thus the closelyadjacent series of emitter/- receivers is aligned to monitor successivetilt positions of each stabilizer arm and the several units areconnected to the indicators on panel 70 similar to the stacked coildevice 45.

Circuit integration of the four tilt-warning devices 45 into a compositewarning or alarm assembly is shown in FIG. 10. It will be understoodthat four of the composite electric eye units of FIGS. 6-8 can besimilarly connected. The first activated coil 59 of each of the units 45is connected to a corresponding warning lamp 75, 76, 77, 78 whichtypically may be a flashing red light which by its position on the panel70 designates the particular area of tilt corresponding to a specificoutrigger stabilizer arm 36, 38, 40, 42. If a primary warning light 75,76, 77, or 78 burns out, loss of ground circuit through the lamp elementcauses the corresponding solenoid 79, 80, 81 or 82 (which is in serieswith the primary lamp) to become de-energised, allowing the normallyopen contact to close and thereby complete a circuit through arespective standby lamp 83, 84, 85 or 86. Successive movement of theinduction mass 65 into the intermediate coil 61 energises the secondstage alert 88 which may be a siren or buzzer. As the piston and itsactivating mass 65 descend into the lowermost coil 63, a climactic orpanic signal is energised, closing the solenoid switch 51 whichenergises the final (lamp or sound) signal F and also locks theBoom-down Control Handle H by means of a solenoid 91 which magneticallyattaches and holds the handle against the metallic sidewall 121 of itsguideway. Such selective locking action of just the boom-loweringfunction (in contrast, for example, to rendering all winch actioninoperative) leaves the operator free to take immediate defensiveaction, as grabbing the Boom-up lever. A test system provides multiplenormally-open switches 72 which are closed by any current flow throughthe solenoid relay 73. Energization is effected by pressing the testbutton 74. An ON-OFF switch 87 and current source 90, plus groundconnections complete the assembly.

FIGS. 11-18 show a single multi-stage or progressively monitoring tiltalarm 92 and self-leveling mount 94 therefor, which in place of theprevious quadruple units of FIGS. 5 and 6 (or in addition thereto ifdesired) can be chassis-attached so as to suspend a pendulumtype unit,the swinging movement of which is registered on a monitoring panel inthe cab 24 so as to show the change of tilt or inclination of thechassis (and hence ofthe whole mobile crane). A cylindrical tubularhousing 95 is formed of insulating material with the inner surface insetat 96 so as to receive bottom-inserted sleeves 97, 98, 99 which areseparated by transverse, centrally apertured disks 100, 101 which thusdelineate internal chambers A, B, C. The housing is closed by a bottomdisk 102 and a dome-shaped cap 103 which is lodged in an annular recess104; the recess additionally supports a juxtaposed pair of disks 105,106 of which the latter is electrically conducting and connected to anexternal cable 93. A dependent central boss 107 of the lower disk isformed with a spherical socket which houses a ball-shaped head 108 of athus suspended pendulum rod 109, both formed of electrically conductingmaterial. An insulating disk 110 having an axiallyprojecting aperturedboss 1 11 embracing the rod, is peripherally attached to fourstabilizing springs 112 which extend to respective anchorage tabs 113which project radially inward from the positioning sleeve 97. Spacedbeneath the stabilizing disk 110 is a larger, electrically conducting,annular plate 114 which is normally centered within a larger centralaperture 115 of the conductive disk 100; the latter by a cable 116 isconnected to an alarm device in the cab 24.

A dependent shield 117 of insulating material houses an electric lamp118, the light from which is directed downward through a restrictedbottom aperture 119. Light passing through the outlet 119 is directed totraverse an axial aperture 120 of the lower disk 101 (thus passing fromcompartment B to compartment C) so as to enter a photo-receiver 122which by a conductor 123 is connected to another alarm device on thepanel 70. It will be seen that an initial or minimum displacement of thelight beam moving through the aperture 119 onto the receiver 122 willsignal a first stage alert such as by activation of one of the panelindicators 75-78. If subsequently the conductor ring 114 makes contactwith the metal plate 100, the audio 88 or panic alarm F is activated(whichever is connected).

The gimbal mount 94 (FIGS. -18) is adapted to initially dispose thetilt-alarm unit 92 in a gravitationally perpendicular position whenattached to the crane chassis, as by a pedestal P, even though thechassis itself may be restingly slanted (or the mounted pedestal may beinclined). A laterally outward and upwardly curved arm 125 with itsbottom end supported atop the pedestal, distally supports a transversesemicircular bow 126, the two ends of which are formed withmutually-aligned open-top grooves 127, 128. A suspension ring 129 isformed with an opposing pair of diagonally outward extending arms 130,131, each having a radially restricted axle projecting therefrom andjournalled in one of said grooves, and with a terminally threadedextension 132, 133 carrying a lock nut 134, 135 which thus can fastenthe ring 129 and arms 130, 131 relative to the bow 126. The alarm unit92 is held by an opposing pair of diametrically aligned pivot pins 136,137 joumalled in grooves of the ring 129 and having terminally threadedends carrying lock nuts 138, 139 for tightening against the ring 129. Itwill be appreciated that by these four lock nuts, the unit 94 and itscontained pendulum are set in a plumb line position prior to use of theunit.

The pendulum construction of FIGS. 19-21 modifies the form of FIGS. 1l14so as to yield two successive sets of tilt indications, both of whichare directional. Either directional set by itself can be substituted inthe form of FIGS. 11-14 so as to provide an assembly with just onedirectional set of indicators but still having a two stage alarm. InFIGS. 19-21 the prior disk 101 and its focussing aperture 120 areeliminated and a directional first stage alert is provided by thephotoreceiver 122a being formed with a ring made by four separate,arcuate shaped, photoreceivers 151, 152, 153, 154, each electricallyconnected to a different tilt-warning indicator in the cab 24. Cabindication of light transmitted to the central area 150 shows when thechassis is approximately level and also serves as a continuous indicatorthat the circuitry is functioning.

The upper indicator disk 100a has its inner edge formed by four arcuateshaped, conductor segments 142, 143, 144, separated by radiallydirected, insulator strips 146, 147, 148, 149 with each segmentelectrically connected to a different second stage, directional tiltindicator on the panel 70. The crane operator can thus learn at oncewith which quadrant the swing ing plate 114 of the pendulum has madecontact, that is, which area of the inclined chassis is down. This maybe in a different quadrant from which the first stage alert wasmonitored due to swinging of the cargo and/or rotation of the crane. Thesecond stage signals from the pendulum may also be connected to lock theBoom-down handle as earlier explained.

In this connection it should be realized that with the mount 94 of FIGS.15-18, the tilt warning device 92 can be itself set initially tilted soas to produce a final alarm by a lesser tilt in one direction than inanother. Thus it can be set to compensate for an inclined ground supporton which the mobile crane may be parked. This is the case when theground support slants downward in the direction of the boom; obviouslythe chassis is already partway inclined toward an upset condition andless additional tilt would be required to topple it. The easyadjustability of the pendulum mount 94 in such event is a veryconsiderable advantage.

While the invention has been particularly described and illustratedherein by reference to its use with a mobile crane which employs acargo-carrying boom, it will be clear that such tilt-warning devices canbe advantageously employed with other equipment having a rotatableangularly-adjustably-upstanding weight-carrying booms, such as thecherry-pickers used by fire departments to rescue persons from highplaces; the tiltwarning devices can be used on the type of buildingwrecking equipment which swings a heavy ball against walls to demolishthem; such tilt-warning devices can likewise be used on earth clearingheavy equipment which has to operate on the sides of steep hills, etc.It is also adapted to floating cranes and marine salvage equipment.

I claim:

l. A device for indicating tilting of a structure on which it ismounted, said device comprising photoelectric emitting means suspendedby a pendulum swingable over an annular area above vertically alignedphotoelectric receiving means electrically connected to a firstsignaling device, said pendulum also carrying an annular electricalconducting element spacedly disposed within a larger surrounding annularelectrical conducting element, contiguity between the two annularelements serving to make a circuit to a second tilt signaling device,whereby the two tilt signaling devices indicate progressive amounts oftilt of said structure.

2. A device according to claim 1 wherein said photoelectric receivingmeans comprises a plurality of photoelectric receivers arranged in agenerally annular pattern and individually connected to separate tiltsignaling devices whereby the direction of tilt of said structure isthus indicated.

3. A device according to claim 2 wherein said annular electricalconducting element comprises separate arcuate segments individuallyconnected to separate second tilt signaling devices.

4. A device according to claim 1 wherein said annular electricalconducting element comprises separate arcuate segments individuallyconnected to separate second tilt signaling devices.

5. A device according to claim 1 in combination with a gimbal mounthaving means for suspending said device with said photoelectricreceiving means disposed selectively horizontal or deliberately slantedtherefrom, regardless of the initial inclination of said structure.

6. A device according to claim I in combination with a crane or the likehaving a rotary platform normally tiltable by reason of an upstandingangularly adjustable boom extending therefrom with means for distallylifting and carrying a heavy article with rotation of the platform, saiddevice being functionally mounted adjacent said rotary platform forindicating directional tilt thereof caused by movement of such boom andheavy article.

7. In a mobile crane or the like having a rotary platform from which anangularly adjustable boom extends with means for distally lifting andcarrying a heavy article with rotation of the platform, and a pluralityof outriggers selectively extensible from a chassis of the crane andadapted for articulated support thereof at tilted positions of thechassis which are variable with the immediate spacial location of theheavy article held by the boom,

the improvement of first means connected to the chassis forprogressively monitoring a tilting condition of the chassis bycontinuously measuring change of its angular position relative to theground or to a chassis-connected structure having ultimate groundsupport, and a plurality of warning devices having means forsuccessively activating same in response to increasing tilt measured bysaid first means, said first means comprising photoelectric emittingmeans suspended by a pendulum above vertically aligned photoelectricreceiving means and electrically connected to a first tilt signalingdevice, said pendulum also carrying an annular electrical conductingelement spacedly disposed within a larger surrounding annular electricalconducting element and both electrically connected to a second tiltsignaling device energisable by contiguity between the two annularelements upon swinging of the pendulum whereby said first and secondtilt signaling devices will indicate progressive amounts of tilt of astructure upon which said first means is mounted.

said photoelectric receiving means comprising a plurality ofphotoelectric receivers arranged in a generally annular pattern areindividually connected to separate first tilt signaling devices wherebythe direction of tilt is thus indicated.

8. A mobile crane according to claim 7 wherein said annular electricalconducting element comprises separate arcuate segments individuallyconnected to separate second tilt signaling devices.

9. A movable vehicle having a chassis-carried rotary platform with anangularly extending weight-carrying boom rotatable therewith, and

a tilt indicating means carried by the vehicle chassis and adapted toindicate successive tilt positions in a plurality of directions aschanged by movement of said boom and weight, means comprisingphotoelectric ernitting means suspended by a pendulum carried by thechassis and swingable over an annular area above a plurality of discretephotoelectric receiving means, said last mentioned means beingelectrically connected to said indicating means.

1. A device for indicating tilting of a structure on which it ismounted, said device comprising photoelectric emitting means suspendedby a pendulum swingable over an annular area above vertically alignedphotoelectric receiving means electrically connected to a firstsignaling device, said pendulum also carrying an annular electricalconducting element spacedly disposed within a larger surrounding annularelectrical conducting element, contiguity between the two annularelements serving to make a circuit to a second tilt signaling device,whereby the two tilt signaling devices indicate progressive amounts oftilt of said structure.
 2. A device according to claim 1 wherein saidphoto-electric receiving means comprises a plurality of photoelectricreceivers arranged in a generally annular pattern and individuallyconnected to separate tilt signaling devices whereby the direction oftilt of said structure is thus indicated.
 3. A device according to claim2 wherein said annular electrical conducting element comprises separatearcuate segments individually connected to separate second tiltsignaling devices.
 4. A device according to claim 1 wherein said annularelectrical conducting element comprises separate arcuate segmentsindividually connected to separate second tilt signaling devices.
 5. Adevice according to claim 1 in combination with a gimbal mount havingmeans for suspending said device with said photoelectric receiving meansdisposed selectively horizontal or deliberately slanted therefrom,regardless of the initial inclination of said structure.
 6. A dEviceaccording to claim 1 in combination with a crane or the like having arotary platform normally tiltable by reason of an upstanding angularlyadjustable boom extending therefrom with means for distally lifting andcarrying a heavy article with rotation of the platform, said devicebeing functionally mounted adjacent said rotary platform for indicatingdirectional tilt thereof caused by movement of such boom and heavyarticle.
 7. In a mobile crane or the like having a rotary platform fromwhich an angularly adjustable boom extends with means for distallylifting and carrying a heavy article with rotation of the platform, anda plurality of outriggers selectively extensible from a chassis of thecrane and adapted for articulated support thereof at tilted positions ofthe chassis which are variable with the immediate spacial location ofthe heavy article held by the boom, the improvement of first meansconnected to the chassis for progressively monitoring a tiltingcondition of the chassis by continuously measuring change of its angularposition relative to the ground or to a chassis-connected structurehaving ultimate ground support, and a plurality of warning deviceshaving means for successively activating same in response to increasingtilt measured by said first means, said first means comprisingphotoelectric emitting means suspended by a pendulum above verticallyaligned photoelectric receiving means and electrically connected to afirst tilt signaling device, said pendulum also carrying an annularelectrical conducting element spacedly disposed within a largersurrounding annular electrical conducting element and both electricallyconnected to a second tilt signaling device energisable by contiguitybetween the two annular elements upon swinging of the pendulum wherebysaid first and second tilt signaling devices will indicate progressiveamounts of tilt of a structure upon which said first means is mounted.said photoelectric receiving means comprising a plurality ofphotoelectric receivers arranged in a generally annular pattern areindividually connected to separate first tilt signaling devices wherebythe direction of tilt is thus indicated.
 8. A mobile crane according toclaim 7 wherein said annular electrical conducting element comprisesseparate arcuate segments individually connected to separate second tiltsignaling devices.
 9. A movable vehicle having a chassis-carried rotaryplatform with an angularly extending weight-carrying boom rotatabletherewith, and a tilt indicating means carried by the vehicle chassisand adapted to indicate successive tilt positions in a plurality ofdirections as changed by movement of said boom and weight, meanscomprising photoelectric emitting means suspended by a pendulum carriedby the chassis and swingable over an annular area above a plurality ofdiscrete photoelectric receiving means, said last mentioned means beingelectrically connected to said indicating means.